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Why small loads matter… …Or how to charge 87,705 electric vehicles a year without additional UK generation capacity. Colin Grenville, director at UKAEE, highlights two examples that show why it is important to keep perspective when pursuing energy efficiency in order to correctly prioritise investment and action

W

hile these are domestic energy usage examples, the principle of having clear energy saving objectives and a well-crafted

plan of action is even more relevant in a business context. Firstly, despite knowing that my job entails helping people save energy, my children are oblivious to applying this fact

in their own world and frequently head out to school leaving their rooms lit up. Naturally, I have tried various approaches to tackle this but short of installing

Figure 1: Daily electricity usage (kWh)

£138

20.0 18.0 16.0

kWh/day linear (kWh/day)

Energy wasted by a 20-yearold freezer compared with a new, A+ rated appliance

14.0 12.0 10.0 8.0

182 GWh

6.0 4.0 2.0

Broken boiler

The saving if 50% of households switched off their broadband router for five hours each night

12

/ 12 / 12 201 7 /0 1/2 0 12 /0 18 2/ 20 12 /0 18 3/ 12 20 /0 18 4/ 20 12 18 /0 5/ 12 201 /0 8 6/ 12 20 /0 18 7/ 20 12 /0 18 8/ 20 12 /0 18 9/ 12 201 /10 8 /2 01 12 8 /11 /2 12 018 /12 /2 0 12 /0 18 1/2 0 12 /0 19 2/ 20 19

0.0

New freezer

Figure 2: Estimated UK home broadband router electricity demand No. of households % with broadband Therefore # of routers Average W/router Average kW/router Total kW demand

27,200,000 98% 26,656,00 7.5 0.0075 199,920 national

BASELINE

Per day

Per year

Tariff/kWh

Annual saving

kWh/router

0.18

65.7

£0.15

£9.86

kWh/national

4,798,080

1,751,299,200

£0.15

£262,694,880

Figure 3: Estimate of potential annual electricity savings Switch off start Switch off end Hours saved/night % of routers switching off

1am 6am 5 7.5

SAVINGS

Per day

Per year

Tariff/kWh

Annual saving

kWh/router

0.0375

13.7

£0.15

£2.05

kWh/national

499,800

182,427,00

£0.15

£27,364,050

50 June/July 2019

occupancy sensors it has limited effect. After berating the kids repeatedly, I sat down and calculated how much energy they were wasting and, as the lights are all LEDs, the answer was not that much since I check regularly and switch them off myself. A 10W load left on for an extra hour a day is only 3.65kWh a year. This led me to undertake a more systematic review of energy-consuming equipment in my home, which revealed the most addressable energy saving opportunity was an old freezer in the garage. Using a simple plug-in power monitor revealed the 20+-year-old appliance was using at least 3kWh every day. After benchmarking against real measurements of a few operational A+ rated freezers, I swiftly realised it was using about five times as much electricity as a modern equivalent and wasting about £130 a year. A high-efficiency replacement was swiftly acquired and the offending appliance removed. It is easy to spot where the new freezer savings start in Figure 1, followed by a further dip while we were on holiday, and then a massive spike due to temporary electric heating when the boiler died. You would think the moral here is “don’t sweat the small stuff ”, which is good advice when there are bigger issues to deal with, but the small loads really do matter over longer time periods or when you look at the impact of many such loads at a national scale. The second example is something found in 98 per

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The Energyst  

July 2019

The Energyst  

July 2019